I can't swear to this as so many vendors at the convention don't prominently display their name and everything was a cash transaction, but I think this (http://www.animebooks.com) was the company I bought mine from. FMA specifically is here (http://www.animebooks.com/fumeal.html). ::is now eyeing the "FMA Complete Story Side" book, which wasn't at the convention::

Also, if you're searching for the Japanese editions, it helps to call the books exactly what's on the covers - "Fullmetal Alchemist TV Animation".